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All Anagrams in a String

Certification: Intermediate Level Accuracy: 0% Submissions: 0 Points: 10

Write a JavaScript program to find all the start indices of anagrams of string p in string s. An anagram is a word formed by rearranging the letters of another word, using all the original letters exactly once. Use the sliding window technique with character frequency counting.

Example 1
    
      
  • Input: s = "abab", p = "ab"
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  • Output: [0, 2]
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  • Explanation: 
    • We need to find anagrams of "ab" in "abab". 
    • At index 0: substring "ab" is an anagram of "ab". 
    • At index 1: substring "ba" is an anagram of "ab". 
    • At index 2: substring "ab" is an anagram of "ab". 
    • Therefore, anagrams start at indices [0, 2].
    •
Example 2
    
      
  • Input: s = "abcab", p = "abc"
    • 
      
  • Output: [0]
    • 
      
  • Explanation: 
    • We need to find anagrams of "abc" in "abcab". 
    • At index 0: substring "abc" is an anagram of "abc". 
    • At index 1: substring "bca" is an anagram of "abc". 
    • At index 2: substring "cab" is an anagram of "abc". 
    • Therefore, anagrams start at indices [0].
    •
Constraints
    
      
  • 1 <= s.length, p.length <= 3 * 10^4
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  • s and p consist of lowercase English letters only
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  • Time Complexity: O(n) where n is the length of string s
    • 
      
  • Space Complexity: O(1) since we only store at most 26 characters
    •
StringsMapCognizantAdobe
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Hint
Solution

Solution Hints

    
      
  • Use sliding window technique with a window size equal to the length of string p
    • 
      
  • Create frequency maps for characters in string p and the current window
    • 
      
  • Slide the window one character at a time across string s
    • 
      
  • When adding a new character, increment its count; when removing, decrement its count
    • 
      
  • Compare frequency maps at each step to check if current window is an anagram
    • 
      
  • Use a helper function to compare two frequency maps efficiently
    •

Steps to solve by this approach:

 Step 1: Create frequency maps for the pattern string p and initialize an empty result array.

 Step 2: Create a sliding window of size equal to p.length and initialize its frequency map.

 Step 3: Check if the initial window forms an anagram with p by comparing frequency maps.

 Step 4: Slide the window one position to the right, adding the new character and removing the old character.

 Step 5: Update the window's frequency map by incrementing count for new character and decrementing for old character.

 Step 6: Compare the updated window frequency map with pattern frequency map to check for anagram.

 Step 7: If frequencies match, add the current window's start index to the result array and continue sliding.

Submitted Code :